package s1280418;

public class Computer {
    private USB[] usbArr=new USB[4];
    public void add(USB usb) {
        for(int i=0;i<usbArr.length;i++){
            if(usbArr[i]==null){
                usbArr[i]=usb;
                break;
            }
        }
    }
    public void powerOn() {
        for(int i=0;i<usbArr.length;i++){
            if (usbArr[i] != null){
                usbArr[i].turnOn();
            }
        }
        System.out.println("计算机开机成功");
    }
    public void  powerOff() {
        for(int i=0;i<usbArr.length;i++){
            if (usbArr[i] != null){
            usbArr[i].turnOff();
            }
        }
        System.out.println("计算机关机成功");
    }

}
